1. Field of the Invention
The present invention relates generally to controlling printing in computers having a MICROSOFT WINDOWS®-type print architecture and, more specifically, to improving the efficiency with which the printer driver and related software elements provide print data to a printer.
2. Description of the Related Art
In a computer operating under the MICROSOFT WINDOWS operating system, an application program can initiate printing by generating a page description and transmitting it to the printer driver. The printer driver is software that operates in conjunction with the operating system and is typically provided by the printer manufacturer. The printer driver converts the page description into a printer-specific data stream.
The printer driver provides the printer-specific data to a spooler, which is part of the operating system. The printer driver typically generates print data in bands or sections, generating data for one part of the page, passing it on to the spooler, and the generating print data for the next part of the page. The printer driver continues this process until print data for the entire page has been generated. The port monitor, which is software that is also typically provided by the printer manufacturer, takes data from the spooler and delivers it to the printer attached to the computer. This combination of a printer driver, spooler and port monitor characterizes the print subsystem of WINDOWS operating systems (WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT, WINDOWS Me, etc.).
The port monitor receives data from the spooler by invoking an application program interface (API) call or function call. The API call is of the blocking type. That is, the port monitor delivers all the data to the printer before returning control to the spooler. As a result of this blocking API call, during the time the port monitor is delivering data to the printer, printer driver operation is suspended. Printer driver operation is suspended because, although WINDOWS is a multi-tasking or multi-threading operating system, independent processes are not used in certain WINDOWS versions (e.g., WINDOWS 95, WINDOWS 98 and WINDOWS Me) to store data in the spooler and read data from the spooler. Rather, the spooler and printer driver operate in the above-mentioned alternating or sequential fashion under a single process: the printer driver generates print data and sends it to the spooler but then is idle or blocked until the port monitor has finished reading the data from the spooler and sending it on to the printer. Multi-threading is not used in this print mechanism because idiosyncrasies of certain versions of the WINDOWS operating system require that the printer driver be implemented in 16-bit code, and the 16-bit components of WINDOWS are not multi-threaded. Therefore, the printer driver is blocked while sending data.
It would be desirable to improve print performance and efficiency in a WINDOWS-type print architecture by minimizing the amount of time that elements of the print architecture are idle. It would further be desirable to do so without altering the WINDOWS operating system itself. The present invention addresses these problems and deficiencies and others in the manner described below.